This invention relates to the field of opto-electronic devices and more particularly to opto-electronic devices with optical micro lenses.
Opto-electronic devices include both emitters and detectors. An opto-electronic emitter is a device that converts an electrical signal into an optical signal. Examples of opto-electronic emitters include light emitting diodes (LEDs) and vertical cavity surface emitting lasers (VCSELs). An opto-electronic detector is a device that converts an optical signal into an electrical signal. Examples of opto-electronic detectors include Charge Coupled Devices (CCDs) and resonant cavity photodetectors (RCPDs).
The development of integrated opto vignetting—electronic devices has made it possible to fabricate multiple opto-electronic devices on a single substrate to form two-dimensional arrays. These two dimensional arrays are useful in a wide variety of applications. For instance, two dimensional arrays of CCDs are often used in digital cameras and imaging equipment, while two-dimensional arrays of VCSELs and RCPDs are used for communication applications which require the switching of optical signals and the interfacing of optical signals with electronic circuits. Techniques for fabricating and using CCDs, VCSELs, LEDs, and RCPDs are well known to those skilled in the art.
When opto-electronic devices are used as arrays of emitters or detectors, a single optical element, or fore lens as it may be called, is often employed to focus or collimate the beams of light to or from the array. Unfortunately, aberrations are often associated with the fore lens. One common aberration is a curvature of field aberration, which causes the light to be focused on a curved surface, such as a sphere, rather than on the surface of a plane. Other more complex aberrations are also common. Prior art methods for compensating for field curvature include implementing a refractive field-flatting element. Unfortunately, these refractive field-flattening elements are both costly and bulky. Therefore, a need exists for an economical and compact method for reducing the curvature of field associated with the fore lens in an optical system.